One particular car brand has been for years touting its safety credentials by pointing out that in a sufficiently severe front collision the engine will drop to avoid entering the passenger capsule (and badly hurting the passengers).

If this were just a twenty-year affair, I might have wondered whether they have perhaps a patent on the drop-engine-upon-impact safety measure.

But since it's been going on for longer, and since other car makers are able to achieve the same (five-star etc) level of safety, there must be other solutions for this problem—or else the other makers have also implemented this method but do not sing its praises.

How do car makers, aside from the one referred to above and which you surely recognize, stop the engine from entering the passenger capsule upon impact?

(This is aside from crumple zones.)


  • @RoryAlsop The Swedish car maker whose name starts with 'V' and whose cars are bulky even by North American standards
    – Sam7919
    Commented Dec 23, 2023 at 16:57
  • @RoryAlsop No. The special feature means that the engine is mounted on bolts that break on impact and stop supporting the engine, enabling it to drop down by gravity, so that the passenger compartment would slide over rather be crushed into it.
    – Sam7919
    Commented Dec 23, 2023 at 17:00
  • @RoryAlsop IIUC The so-called "crumple zones" are present in all cars—front and rear. These absorb the energy of impacts for lower speeds (say up to 80 km/hr ~ 50 mile/hr) and avoid passenger neck injuries (etc). In more severe front collisions, crumple zones are insufficient, hence the need to worry about where the engine block goes.
    – Sam7919
    Commented Dec 23, 2023 at 17:03
  • 1
    @Sam7919 Drop by gravity? The math says no. A vehicle that crashes into a solid object at just 25 mph would have its engine compartment contents pushed back 2 feet in 55 milliseconds. Two feet puts the engine in the passenger compartment. But an object falling by gravity alone moves down just a little more than half an inch in the first 55 ms. (4 ft, 110 ms = a 2" drop, and still not enough.) If the ad's claim is true, something other a free-falling engine moved only by gravity must be at play, such as structural elements that bend preferentially downward, taking the engine with them.
    – MTA
    Commented Dec 23, 2023 at 18:49
  • 1
    In the head on collision as I described in my answer the force is directed at the passenger compartment and dissipated by the engine as illustrated in the image of the vehicle being dropped 100 ft. In the other photo where the engine is a lateral impact where the force is directed at the engine itself and the applicable sheer forces come into play and detaches the engine. Hit by the car the becomes a projectile then Newton Laws applies
    – Old_Fossil
    Commented Dec 27, 2023 at 4:47

1 Answer 1


The year: 2007 The vehicle: 2001 Toyota Corolla CE 5sp Manual transvere mounted engine

Based on personal experience I survived a head on collision with a drunk driver. The impact was at 110 kmh (68mph). Photos taken after the fact showed the engine inside the engine compartment slammed up against the firewall after being sheared of the engine mounts. Effectively the engine mass reinforced the firewall. Incredible but true it was only the front end that was damaged up the the front wheels.

The only injuries sustained were as follows: 2 fractured ribs,a brutal seat belt burn, cardiac arrest due to air bag deployment, bone fragments in both ankles and both wrists. I came back 3 and a half minutes later due to amount of Adrenalin that kick started my heart.

The guys at work used to kid me about tie wrapping hub caps. After such a high speed impact all the hub caps were attached and intact.

I was so impressed by the car I presently driving my 3rd one.

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